Studies on the properties of two intracellular serine proteases from Bacillus subtilis

Intracellular serine protease-1 (ISP-1) from Bacillus subtilis had been previously purified to homogeneity. The purified protease (Mr = 31,000) had undergone processing to remove 17 to 20 amino-terminal amino acid residues. Then observations and a number of other studies led to the proposal that ISP-1 is synthesized in B. subtilis cells as an inactive precursor, which may undergo activation by amino-terminal processing. To examine these questions, monospecific polyclonal antibodies against ISP-1 were raised. A variety of procedures for extracting ISP-1 from cells under conditions that prevent proteolysis in vitro were evaluated by immunobloting and ISP-1 activity assays. ISP-1 was found to be always produced in a form (Mr = 34,000) that was larger than the purified form. This larger form was readily converted to the smaller form in vitro in crude extracts at pH 8.5 in the presence of Ca$\sp{2+}$ ions. It was also found that the appearance of ISP-1 activity and immunologically cross-reactive protein were temporally coincident. Thus, amino-terminal processing of ISP-1 is an artifact of in vitro proteolysis, and no evidence for an inactive ISP-1 precursor was found.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Biochemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Sheehan, Shannon Mark

Contributors dc:contributor

• Switzer, Robert L.

• Biology, Microbiology
• Chemistry, Biochemistry

Statement dc:rights

• Copyright 1990 Sheehan, Shannon Mark

Language dc:language

eng

Identifier

AAI9114409
(UMI)AAI9114409

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/19577